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//===-- JSONTransport.cpp -------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Host/JSONTransport.h"
#include "lldb/Utility/IOObject.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/SelectHelper.h"
#include "lldb/Utility/Status.h"
#include "lldb/lldb-forward.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/raw_ostream.h"
#include <optional>
#include <string>
#include <utility>
using namespace llvm;
using namespace lldb;
using namespace lldb_private;
/// ReadFull attempts to read the specified number of bytes. If EOF is
/// encountered, an empty string is returned.
static Expected<std::string>
ReadFull(IOObject &descriptor, size_t length,
std::optional<std::chrono::microseconds> timeout = std::nullopt) {
if (!descriptor.IsValid())
return llvm::make_error<TransportInvalidError>();
bool timeout_supported = true;
// FIXME: SelectHelper does not work with NativeFile on Win32.
#if _WIN32
timeout_supported = descriptor.GetFdType() == IOObject::eFDTypeSocket;
#endif
if (timeout && timeout_supported) {
SelectHelper sh;
sh.SetTimeout(*timeout);
sh.FDSetRead(
reinterpret_cast<lldb::socket_t>(descriptor.GetWaitableHandle()));
Status status = sh.Select();
if (status.Fail()) {
// Convert timeouts into a specific error.
if (status.GetType() == lldb::eErrorTypePOSIX &&
status.GetError() == ETIMEDOUT)
return make_error<TransportTimeoutError>();
return status.takeError();
}
}
std::string data;
data.resize(length);
Status status = descriptor.Read(data.data(), length);
if (status.Fail())
return status.takeError();
// Read returns '' on EOF.
if (length == 0)
return make_error<TransportEOFError>();
// Return the actual number of bytes read.
return data.substr(0, length);
}
static Expected<std::string>
ReadUntil(IOObject &descriptor, StringRef delimiter,
std::optional<std::chrono::microseconds> timeout = std::nullopt) {
std::string buffer;
buffer.reserve(delimiter.size() + 1);
while (!llvm::StringRef(buffer).ends_with(delimiter)) {
Expected<std::string> next =
ReadFull(descriptor, buffer.empty() ? delimiter.size() : 1, timeout);
if (auto Err = next.takeError())
return std::move(Err);
buffer += *next;
}
return buffer.substr(0, buffer.size() - delimiter.size());
}
JSONTransport::JSONTransport(IOObjectSP input, IOObjectSP output)
: m_input(std::move(input)), m_output(std::move(output)) {}
void JSONTransport::Log(llvm::StringRef message) {
LLDB_LOG(GetLog(LLDBLog::Host), "{0}", message);
}
Expected<std::string>
HTTPDelimitedJSONTransport::ReadImpl(const std::chrono::microseconds &timeout) {
if (!m_input || !m_input->IsValid())
return llvm::make_error<TransportInvalidError>();
IOObject *input = m_input.get();
Expected<std::string> message_header =
ReadFull(*input, kHeaderContentLength.size(), timeout);
if (!message_header)
return message_header.takeError();
if (*message_header != kHeaderContentLength)
return createStringError(formatv("expected '{0}' and got '{1}'",
kHeaderContentLength, *message_header)
.str());
Expected<std::string> raw_length = ReadUntil(*input, kHeaderSeparator);
if (!raw_length)
return handleErrors(raw_length.takeError(),
[&](const TransportEOFError &E) -> llvm::Error {
return createStringError(
"unexpected EOF while reading header separator");
});
size_t length;
if (!to_integer(*raw_length, length))
return createStringError(
formatv("invalid content length {0}", *raw_length).str());
Expected<std::string> raw_json = ReadFull(*input, length);
if (!raw_json)
return handleErrors(
raw_json.takeError(), [&](const TransportEOFError &E) -> llvm::Error {
return createStringError("unexpected EOF while reading JSON");
});
Log(llvm::formatv("--> {0}", *raw_json).str());
return raw_json;
}
Error HTTPDelimitedJSONTransport::WriteImpl(const std::string &message) {
if (!m_output || !m_output->IsValid())
return llvm::make_error<TransportInvalidError>();
Log(llvm::formatv("<-- {0}", message).str());
std::string Output;
raw_string_ostream OS(Output);
OS << kHeaderContentLength << message.length() << kHeaderSeparator << message;
size_t num_bytes = Output.size();
return m_output->Write(Output.data(), num_bytes).takeError();
}
Expected<std::string>
JSONRPCTransport::ReadImpl(const std::chrono::microseconds &timeout) {
if (!m_input || !m_input->IsValid())
return make_error<TransportInvalidError>();
IOObject *input = m_input.get();
Expected<std::string> raw_json =
ReadUntil(*input, kMessageSeparator, timeout);
if (!raw_json)
return raw_json.takeError();
Log(llvm::formatv("--> {0}", *raw_json).str());
return *raw_json;
}
Error JSONRPCTransport::WriteImpl(const std::string &message) {
if (!m_output || !m_output->IsValid())
return llvm::make_error<TransportInvalidError>();
Log(llvm::formatv("<-- {0}", message).str());
std::string Output;
llvm::raw_string_ostream OS(Output);
OS << message << kMessageSeparator;
size_t num_bytes = Output.size();
return m_output->Write(Output.data(), num_bytes).takeError();
}
char TransportEOFError::ID;
char TransportTimeoutError::ID;
char TransportInvalidError::ID;
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